Digoxin

What is digoxin?

Digoxin is a prescription-only medication for heart failure or chronic atrial fibrillation, a type of irregular heartbeat.

It belongs to the cardiac glycosides class of medications.

Digoxin is a generic medication. It is sold under brand names like Digitek and Lanoxin in the US.

Generic digoxin comes in the following dose formats:¹

• Oral solution: 60ml (0.05mg/mL)

• Tablet: (62.5mcg, 125mcg, 250mcg)

What is digoxin used to treat?

The drug is approved by the US Food and Drug Administration (the FDA) for the following three purposes:²

• To treat mild to moderate heart failure in adults (usually taken with other medications)

• To improve myocardial contractility (cardiac muscle contractions) in children with heart failure

• To treat chronic atrial fibrillation (a type of irregular heartbeat)

How does digoxin work?

Digoxin works by helping people with heart failure pump enough blood and oxygen around their bodies. It does so by blocking an enzyme in the heart that causes it to pump harder with each beat.

The medication helps people with atrial fibrillation by slowing electrical activity in the heart.

How do you take digoxin?

Take digoxin exactly as your doctor prescribes. Do not start or stop taking this medicine without medical guidance. Do not take more or less than your prescribed dose.

Digoxin is usually taken once a day.² Read the label carefully for how to take this medicine.

The dosage your doctor recommends will depend on the condition being treated, your age, kidney function, weight, and any other medications you take. You may need to have a blood test to check your digoxin blood level and ensure you are receiving the correct dose. 

Swallow the tablets whole with water.

Measure the oral liquid solution with the medical syringe that comes with your medication — if not, ask your doctor or pharmacist to provide one. Don’t dilute the solution.

Seeing results

Your symptoms may start to improve after a few weeks of taking digoxin.³ For some conditions, it may take several months for your symptoms to improve.

Inform your doctor and ask for advice if your symptoms do not improve after several months of taking digoxin.

Remember not to stop taking your medication without your doctor’s guidance, even if you start feeling better.

Potential side effects of digoxin

Like most medicines, digoxin can cause side effects. Some are common and may ease on their own, while others suggest you need medical attention.

Digoxin side effects are more common in people who take a higher dose than recommended.⁴ Your doctor may require you to have a blood test to check the level of digoxin or potassium in your blood to avoid digoxin toxicity.

Tell your doctor if you develop these side effects and they become severe or don’t go away on their own:⁵

• Feeling lightheaded or dizzy

• Drowsiness

• Blurred or yellow vision

• Rash

• Irregular heartbeat or palpitations

Call your doctor immediately if you develop any of these serious side effects:

• Difficulty breathing

• Upset stomach

• Diarrhea

• Vomiting

• Loss of appetite

• Unexplained weight gain

• Swollen hands or feet

Your doctor may monitor you to check the digoxin levels in your blood are within a normal range.

Long-term use of digoxin

Digoxin is intended to be used as a long-term treatment. Ensure you follow your doctor or pharmacist’s recommendations carefully to help you take this drug safely.

Missed doses

If you miss a dose of digoxin, take it as soon as you remember. If it’s nearly time for your next dose, skip the dose you missed and resume your regular schedule.

Never take two doses at once to make up for the one you missed.

Talk to your doctor if you find you miss doses regularly.

Overdoses

Taking too much digoxin can cause digoxin toxicity, a condition where too much digoxin has accumulated in the blood.

A digoxin overdose may cause the following symptoms:⁶

• Nausea

• Vomiting

• Irregular heartbeat

• Tiredness⁷

• Hyperkalemia (high potassium levels) — signs include chest pain, stomach pain, diarrhea, nausea, vomiting, irregular heartbeat, heart palpitations, and an irregular, fast, or fluttering heartbeat

Seek emergency medical assistance if you think you or someone else has taken too much digoxin.

Allergy information

Digoxin can cause an allergic reaction. Symptoms of an allergic reaction include:⁸

• Rash

• Hives

• Swelling of the face, mouth, tongue, lips, or throat

• Difficulty breathing

• Wheezing

• Difficulty swallowing

• Difficulty talking

• Tightness in your throat or chest

• Skin that is itchy, red, blistered, peeling, or swollen

If you experience an allergic reaction when taking digoxin, immediately stop using it and seek medical help. You may be prescribed another type of medicine.

What to discuss with your doctor before taking digoxin

Before you start taking digoxin, be sure to discuss the following things with your doctor if they apply to you:

• Allergies: You must tell your doctor if you are allergic to digoxin or any other medications.

• Other medications: Digoxin interacts with several other drugs. You should tell your doctor about other medications (prescription or over-the-counter), supplements, or herbal remedies you are currently taking or plan to take during digoxin treatment.

• Other medical conditions: Tell your doctor about all your previous or current medical conditions, including thyroid problems, cancer, kidney disease, or heart arrhythmias. 

• Scheduled surgery, including dental surgery.

• Pregnancy and breast-feeding: Tell your doctor if you are pregnant, planning to become pregnant, or you are currently breastfeeding.

Before taking digoxin, ensure you know how to take it safely. Ask your doctor about any possible side effects and risks.

Stopping digoxin

Do not stop taking digoxin without your doctor’s guidance. Doing so may worsen the symptoms of your condition.

Consult your doctor and ask for instructions if you would like to stop taking this medication. You may be prescribed a gradually decreasing dose to avoid adverse effects.

Who should not take digoxin

Digoxin might not be suitable for you if:

• You have Wolff-Parkinson-White syndrome — digoxin may cause ventricular fibrillation (a serious heart rhythm problem).⁹

• You have sinus node dysfunction — digoxin may cause sinus bradycardia or sinoatrial block.

• You have a partial atrioventricular (AV) block — digoxin may cause a complete AV block.

• You are having a heart attack (acute myocardial infarction) — digoxin may cause ischemia (where your heart doesn’t get enough blood).

• You have an inflamed heart muscle (myocarditis) — digoxin may constrict your blood vessels.

• You have a certain type of heart failure called heart failure with preserved ejection fraction (HFpEF) — digoxin may cause decreased cardiac output.

• You have impaired kidney function — increases the risk of digoxin toxicity (your doctor may prescribe a lower dosage).

• You have low calcium levels (hypocalcemia) — digoxin may not be effective in people with hypocalcemia. Calcium levels may need to return to normal levels before treatment.

• You have a thyroid condition —digoxin may not be effective in people with an underactive (hypothyroidism) or overactive (hyperthyroidism) thyroid.

Digoxin and pregnancy

Digoxin is an FDA pregnancy category C medication.¹⁰ This means the drug has been found to cause fetal harm in animal studies, but more human research is needed.

You may be prescribed digoxin during pregnancy if the benefits outweigh the risks. Too much digoxin in your blood could affect your baby, so you may be asked to undergo regular blood tests.

Digoxin and breastfeeding

Digoxin is known to pass into breast milk, but only in small amounts.¹¹ Since there are no known risks, you may still be able to take digoxin while breastfeeding.

Consult your doctor if your baby seems unusually sleepy or is not feeding well.

Interactions with other drugs

Certain medications interact with digoxin. Some increase the amount of digoxin in your body and increase your risk of side effects.

Digoxin is known to interact with the following drugs:¹² ¹³

Heart medications, like:

• Amiodarone (Pacerone or Cordarone)

• Adenosine (Adenocard or Adenoscan)

• Dofetilide (Tikosyn)

• Propafenone (Rythmol)

• Dronedarone (Multaq)

• Sotalol (Sorine or Betapace)

• Quinidine

• Ivabradine (Corlanor)

HIV medications, like:

• Atazanavir (Reyataz)

• Saquinavir (Invirase)

• Ritonavir (RTV)

Blood pressure drugs, like:

• Carvedilol (Coreg)

• Captopril

• Diltiazem (Cardizem, Taztia, Tiazac, and others)

• Nifedipine (Afeditab CR, Adalat CC, Nifedical XL, or Procardia XL)

• Verapamil (Calan, Verelan, or Covera HS)

• Spironolactone (Carospir or Aldactone)

• Telmisartan (Micardis)

Antibiotics, like:

• Clarithromycin (Biaxin)

• Azithromycin (Zmax or Zithromax)

• Gentamicin

• Erythromycin (EES)

• Trimethoprim (Primsol)

• Tetracycline (Achromycin V)

Antifungal drugs, like:

• Ketoconazole (Nizoral)

• Itraconazole (Onmel or Sporanox)

Nonsteroidal anti-inflammatory drugs (NSAIDs), like:

• Ibuprofen (Advil, Motrin, and others)

• Indomethacin (Tivorbex or Indocin)

• Diclofenac (Zipsor, Zorvolex, or Cambia)

Proton pump inhibitors, like:

• Esomeprazole (Nexium)

• Rabeprazole (AcipHex)

• Omeprazole (Prilosec)

• Lansoprazole (Prevacid)

Some sphingosine l-phosphate receptor modulator drugs, like:

• Fingolimod (Gilenya)

• Ponesimod (Ponvory)

• Siponimod (Mayzent)

Stimulant drugs, like:

• Norepinephrine

• Phenylephrine (Sudafed and others)

• Epinephrine (EpiPen and others)

Other drugs that interact with digoxin include:

• Ceritinib (Zykadia) — used to treat non-small cell lung cancer

• Calcium chloride, calcium gluceptate, and calcium gluconate

• Dolasetron (Anzemet) — a serotonin 5-HT3 receptor antagonist used to prevent some side effects of chemotherapy

• Parathyroid hormone injections (Natpara) — used in people with some types of hypoparathyroidism to raise blood calcium levels

• Flibanserin (Addyi) — a drug used to treat hypoactive sexual desire disorder (HSDD) in women

• Lapatinib (Tykerb) — a drug used to treat a certain type of advanced breast cancer

• Succinylcholine (Anectine) — a neuromuscular blocker

Note that this is not the complete list of medicines that interact with digoxin. 

Drug approval history

Digoxin was first isolated from the foxglove plant, Digitalis purpurea, by Dr Sydney Smith in 1930.¹⁴

The FDA first approved digoxin as an injectable drug to be sold under the brand name Lanoxin in 1954. Since then, it has been approved in other forms, including an oral tablet and solution.

Due to its numerous drug interactions and requirement for close monitoring, digoxin is now considered adjunctive therapy rather than first-line therapy.¹⁶ Therefore, it may be prescribed alongside other drugs.

Tips and advice for taking digoxin

Follow these tips to help you take digoxin safely and effectively:

• Take digoxin according to your doctor’s instructions. Do not start or stop taking this drug without your doctor’s recommendation.

• Take digoxin at the same time each day.

• Keep to your medical appointments to ensure you are monitored while taking this medication. Too much digoxin in your bloodstream could cause complications.

• Ensure you drink enough water to keep hydrated while taking this medicine.